While child maltreatment affects almost 1 million children each year, and constitutes a serious public health problem in the U.S., evidence from meta-analysis suggests that interventions for child maltreatment do little to strengthen the quality of interactions between maltreating parents and their children. We propose to study patterns of interactive synchrony, rupture, and repair in transactions between maltreating mothers and their preschool children in order to improve the identification of child risk for negative self-regulatory and behavioral outcomes, and facilitate prescriptive matching of early interventions to specific types of disruptive interactions in maltreating mother-child dyads. The sample consists of 250 mothers and their 3-5 year old children. One hundred-fifty (150) maltreating mother-child dyads will be drawn from Children &Youth Service agencies (i.e., mothers identified as perpetrators of physical abuse or neglect, and representing a range of maltreatment severity). One hundred (100) non-maltreating mother-child dyads matched on key socio-demographics will also participate. Mother-child interactions during a series of unstructured and compliance tasks will be assessed during a home visit and subsequent laboratory session, and coded via the Structural Analysis of Social Behavior (SASB) for extent of interactive coordination, and patterns of relationship rupture and repair. Physiological and behavior measures of regulation (i.e., emotion regulation, baseline cardiac vagal tone, vagal regulation, behavioral control), and problem behavior will be collected from children. Neurophysiological and survey-based indices of parent regulation (i.e., baseline cardiac vagal tone, vagal regulation, effortful control) will also be obtained. Analyses will be used to (1) empirically determine classes of dyadic interactive coordination, rupture, and repair in maltreating dyads that distinguish subtype and level of maltreatment severity;assess (2) relations between mother-child interactions and child emotion regulation and behavior;and (3) examine relations among parent regulation, dyadic interactions, maltreatment, and child outcomes. This innovative project addresses gaps in the maltreatment literature by: (a) examining patterns of parent-child interactive coordination associated with severity and subtype of maltreatment;(b) combining neurophysiological and behavioral assessment of emotion regulation in maltreating mothers and their preschool children;(c) using advanced micro-analytic coding technologies and state-of-the-art statistical methods to model patterns of interactive synchrony, rupture, and repair that unfold over time in the sequential interactions between maltreating mothers and their preschool children;and (d) examining the bi-directional influence of mother and child during these inter- changes. Following conclusion of this project, we plan to develop testable interventions to target specific patterns of interactive disruption in maltreating families.